Means for guarding needle latches of circular knitting machines

ABSTRACT

In a circular knitting machine there is provided a latch guard devoid of feeder receiving slots but formed instead at a knitting station or each of a plurality of knitting stations with a slot just wide enough to receive a yarn and permit two yarns to pass during a yarn change. Thereby the risk of the latches of latch needles becoming damaged by swinging into latch guard slots during operation of the machine is avoided.

0 United States Patent [151 3,667,256

Townsend et al. 51 June 6, 1972 54] MEANS FOR GUARDING NEEDLE 1,509,408 9 1924 Miller ..66/l 12 C S OF CIRCULAR KNITTING 621,681 3/1899 .lohnsm. ....66/1 11 MACHINES 670,892 3/1901 Clarke ....66/l ll X 456,372 7/1891 Bennor ....66/1 11 X 72 Inventors; K i h Gerald Townsend; David Arthur 805,670 1 l/ 1905 Rowe ..66/1 1 1 X l b f Lemme" England FOREIGN PATENTS OR APPLICATIONS [73] Assignee: The Bentley Engineering Company 7 Limited Leicester England 1,019,160 2/1966 Great Britain ..66/l l l [22] Filed: Apr. 20, 1970 Primary Examiner-Wm. Carter Reynolds 1 pp No; 30,177 Attorney-Robert E. Burns and Emmanuel J. Lobato [57] ABSTRACT [30] Foreign Apphcauon Pnonty Data In a circular knitting machine there is provided a latch guard Apr. 23, 1969 Great Britain ..20,684/69 devoid of feeder receiving $1915 but formed instead a! a knitting station or each of a plurality of knitting stations with a 52] slot just wide enough to receive a yarn and permit two yarns to 51] pass during a yarn change. Thereby the risk of the latches of [58] Field of Search ..66/1 1 1, 1 12 latch needles becoming damaged y Swinging into latch guard slots during operation of the machine is avoided. [5 6] Remences 6 Claims, 3 Drawing Figures UNITED STATES PATENTS 2,757,526 8/1956 Crawford ..66/1 11 X PATENTEDJUH s 1912 SHEET 10F 2 ELL/- PATENTEnJun a ma sum 2 of 2 MEANS FOR GUARDING NEEDLE LATCHIE OF CIRCULAR KNITTING MACHINES This invention is for an improved means for guarding needle latches of circular knitting machines, and is particularly applicable to use on single cylinder knitting machines for knitting hosiery footwear such as socks and stockings. The invention seeks to reduce or eliminate certain disadvantages present with latchguards on existing machines.

On single cylinder machines for knitting hosiery footwear it has been the practice to form a U-shaped slot in the usual latchguard ring at least at the main feed position to accommodate yarn feeders through which yarns are fed, as required, to the needles. Such a slot is sufficiently deep to allow needles arriving at tucking height to have their hooks sufficiently above the bottom of the slot to enable them to receive yarn from a feeder and needles arriving at clearing height have their hooks well above the bottom of the slot and can take yarn as the needles descend to draw stitches. The yarn is ordinarily fed from a feeder via a lower comer of the U-shaped slot on its way into the hooks of the needles and it has been found advantageous to make the bottom of the slot of a hard wearing metal or other material such as ceramic in the form of an insert which can easily be replaced. The slots in the latch guard forrn recesses into which needle latches can swing when the needles are at certain heights, especially in the event of a press-off'"or in the case of any individual needles in the machine not actually knitting yarn. If a needle latch enters the slot it is very prone to be bent as it hits the far side thereof and considerable damage to the needles can well occur involving wasteful delay and replacement expense. This difficulty can be encountered during continuous rotary knitting and also during reciprocatory knitting, but in the latter case a gap closer has been used in the form of an arcuately slidable member which can move to and fro. Such gap closer not only requires to be carefully fitted but also offers the disadvantage of being liable to collect lint and dirt. The invention seeks to provide improved means for guarding needle latches at all times in which the aforementioned disadvantages are largely or wholly overcome.

In accordance with the invention there is provided in a circular knitting machine a latch guard which is devoid of feeder receiving slots but has at a feeding station a slot just wide enough for yarn to be fed through it (and for two yarns to pass at a yarn change), the width of the slot being insufficient to permit a needle latch to swing into it during operation of the knitting machine. Conveniently the latch guard is in the form of a ring which presents to the needles a cylindrical surface which is devoid of gaps capable of damaging needle latches during knitting at any level of the needles. Thus the needle latches are prevented from being caught up in gaps or recesses in the latch guard so that the aforementioned liability to damage of the latches is avoided. Moreover in the case of a machine which is required to perform reciprocatory knitting, the need for providing a gap closing member as aforementioned is avoided.

In practising the invention there may be provided a latch guard ring which at the position of a yarn feeding station is formed with a narrow heightwise extending slot opening on to one of its edges to permit passage therethrough of a yarn on its way from a feeder to the needles. In the case of a machine having a plurality of feeding stations the ring will be formed with such a slot at the position of each feeding station. Advantageously such a latch guard ring may be provided with means for ensuring that a yarn or yarns passing through such a slot cannot escape therefrom. Such means may consist of a ring encircling the latch guard ring at or near the mouth of the slot or slots as aforesaid therein, or may be provided by having the slot or slots closed at the upper end.

A convenient form of construction in accordance with the invention is illustrated by way of example in the accompanying drawings in which:

FIG. 1 is a plan view of the top of a single cylinder circular knitting machine such as is used for knitting hosiery footwear,

FIG. 2 is a detail elevation view in cross-section taken on the line II-II in FIG. 1, and

FIG. 3 is a fragmentary cross-sectional view of a modified latch guard ring.

Only a sufficient part of the knitting machine is shown in the drawings to enable the provisions of the invention to be understood. As can be seen from FIG. 2, there is a circular series of needle 1 located in a needle cylinder 2, and rotatable with the cylinder past operating cams (not shown) to impart the various knitting movements which are well known and do not need to be described herein. Around the periphery of the top of the needles is a latch guard in the form of a cylindrical ring 3 the surface of which is continuous around its lower edge adjacent to the sinkers shown at 4 in FIG. 2 but is slotted from its upper edge at locations 35 and 313 etc, in parts of the ring 3 that are externally and vertically recessed at 21 to form a thin wall part. The slots 32 and 32 etc are only as wide as a normal feeder hole, i.e. of sufficient width to allow free passage of the yarn and to allow two yarns to pass one another. The tops of the slots may be effectively closed by the use of a circumferential band 5 held in a groove 6around the outside of the latch guard ring. Various forms of slot closure may be used; it is even possible to manufacture the latch ring with slots closed at both ends (as will be described later).

The latch guard ring 3 is bolted to a support plate 22 from which extend arms 22g and 22; supporting it from a spindle l2.

The parts illustrated will now be described more particularly with reference to the main feeding position as denoted at A on FIG. 1, the same description in general being applicable to all other feeding positions. At the outside of the latch guard ring are located the main feed feeders 7,8,9,10,l 1, all of which are pivoted on the spindle 12 and operated by links or cables from the main or auxiliary control drum as is conventional on such machines but not shown here. Associated with each feeder is a trapper located within the needle circle as shown in FIG. 1 at 13, 14,15,16 and 17, related respectively to the feeders 7,8, 9,10 and 11.

The yarns which are not being fed to needles at any one time pass through the feeders which are held in their high inactive position, through the slot 3 z in the latch ring 3 to the appropriate trapper, such as is shown in FIG. 2 by the position of feeder 10 and yarn 18. These inactive yarns are held from rising out of the top of slot 35 by the band 5. The yarn or yarns which are being knitted by the needles are kept low in slot 35 to cause them to enter the hooks lg of the needles, as is shown in FIG. 2 by yarn 19 fed through the active feeder 9. To change yarns being fed the conventional movements of feeders and trappers are carried out, each yarn passing through the guide slot 205 in plate 20 to its respective trapper and the feeders reversing their positions as needed.

It can be seen from this description that the edges of the slots such as 35 perform the same function of guiding the yarn as do the comers of a conventional throat plate. It is therefore necessary to make the latch guard ring of very hard metal or to fit ceramic inserts at the sides of the feeding slots to prevent wear.

In the modified construction shown in FIG. 3 a cylindrical latch guard ring 23 is supported at three positions spaced apart around its circumference by flanged nuts 25, screwed for adjustability on studs 26, and fitted with locking nuts 25g. Flanges 24 of the nuts 25 engage in scalloped grooves 27 in the ring 23 to support the latter. The studs 26 pass through holes formed in intumed lugs 28 of a latch ring 29 pivoted on a spindle corresponding to spindle 12. Springs 30 on the studs 26 are in compression between the heads of the studs and the lugs 28 when the latch ring is lowered to and locked in its working position thereby holding the heads of the studs against the support plate 22 which may be the sinker cap. At the locations of feeders the latch guard ring is formed with external and vertical recesses 31, like the recesses 21, and yarn receiving slots 32 corresponding to the slots 39, 32 etc of FIG. 1, but differing therefrom by being closed at both upper and lower ends as indicated at 329 and 3213. By having both ends of the slots 32 closed less weakening of the ring is caused by the slots.

Another alternative form of latch guard ring in accordance with this invention which can be used if the design of the knitting machine so permits, is of the same form as in FIGS. 1 and 2 but made taller. With such a modified latch guard ring it is not necessary to restrict the height to which the yarns rise in the slot or to chamfer the top edges of the slot to guide the yarns into it, as the feeder levers are not able to lift the yarns near enough to the top of the slot to introduce any risk of them escaping from the slot What we claim is:

1. In a circular knitting machine equipped with latch needles the combination comprising a latch guard ring of cylindrical form and mounting means therefor, said latch guard ring being recessed vertically externally to reduce it to a thin wall part at a position corresponding to a knitting station and formed in said thin wall part with a narrow vert-yarn feeding slot just wide enough for a yarn to pass through it and for two yarns to pass one another vertically during a yarn change and narrow enough to prevent a needle latch from swinging into the slot during operation of the machine.

2. The combination as claimed in claim 1 wherein the slot in the latch guard ring at a yarn feeding station for passage of a yarn opens on to the upper edge of the ring, and a circumferential band surrounds the upper part of the latch guard ring to ensure that a yarn or yarns passing through said slot cannot escape through its open end.

3. The combination as claimed in claim 1, wherein the said narrow heightwise extending slot is famed with its upper and lower ends closed to retain the yarn or yarns therein.

4. The combination as claimed in claim 1 in a machine having a plurality of feeding stations and having the latch guard ring reduced externally to a thin wall part and formed with a narrow vertical slot at each position corresponding to that of a feeding station. 7

5. The combination as claimed in claim 1 having a latch ring surrounding the latch guard ring and spaced outwardly therefrom and three inwardly directed lugs spaced apart on the latch ring to provide mountings for the latch guard ring.

6. The combination as claimed in claim 5, comprising bolts carried in holes in said lugs and flanged nuts on said bolts with the flanges of said nuts engaging in external grooves in said latch guard ring to support the latter.

* l III 

1. In a circular knitting machine equipped with latch needles the combination comprising a latch guard ring of cylindrical form and mounting means therefor, said latch guard ring being recessed vertically externally to reduce it to a thin wall part at a position corresponding to a knitting station and formed in said thin wall part with a narrow vert-yarn feeding slot just wide enough for a yarn to pass through it and for two yarns to pass one another vertically during a yarn change and narrow enough to prevent a needle latch from swinging into the slot during operation of the machine.
 2. The combination as claimed in claim 1 wherein the slot in the latch guard ring at a yarn feeding station for passage of a yarn opens on to the upper edge of the ring, and a circumferential band surrounds the upper part of the latch guard ring to ensure that a yarn or yarns passing through said slot cannot escape through its open end.
 3. The combination as claimed in claim 1, wherein the said narrow heightwise extending slot is formed with its upper and lower ends closed to retain the yarn or yarns therein.
 4. The combination as claimed in claim 1 in a machine having a plurality of feeding stations and having the latch guard ring reduced externally to a thin wall part and formed with a narrow vertical slot at each position corresponding to that of a feeding station.
 5. The combination as claimed in claim 1 having a latch ring surrounding the latch guard ring and spaced outwardly therefrom and three inwardly directed lugs spaced apart on The latch ring to provide mountings for the latch guard ring.
 6. The combination as claimed in claim 5, comprising bolts carried in holes in said lugs and flanged nuts on said bolts with the flanges of said nuts engaging in external grooves in said latch guard ring to support the latter. 